Digital Chest X-ray Research Articles

Are we focusing on the wrong end of neonatal endotracheal tube?

Aim To test the hypothesis that: The black mark at the tip of endotracheal tube guides the optimal insertion distance during neonatal intubation. Background There are several formulae and graphs that are used to calculate the length of orally or nasally inserted endo-tracheal tube (ETT) in a neonate. These aim to place the in tip in mid-tracheal position (or against T2 vertebra) on chest x-ray. It is widely practised that the black mark at the end of ETT is the appropriate depth for insertion. Our unit uses VYGON tubes and the black mark begins at 7 mm and ends at 25 mm distance from the tip in tubes of all sizes. Method The authors retrospectively studied CXRs of sequential neonates who were admitted to the neonatal unit over 8 months. The admission CXR was studied if the exposure contained neck and chest, regardless of whether intubated or reason for admission. The authors attempted to predict the distance of mid-trachea from vocal cords by studying digital chest x-rays (CXR). Neonatal vocal cords are super-imposed against C4 vertebra on frontal CXR. We estimated the vocal cord to mid-trachea distance from middle of C4 vertebra to middle of T2 vertebra. The C4 to T2 measurements were plotted on a scatter chart against the birth weight. Results The authors obtained x-rays for 78 babies with a weight range from 560 to 4160 g. The authors found that even in the smallest neonates, mid-trachea lies 15 mm below vocal cords, whereas this distance is 35 mm in the large term babies. There is a linear relation with birth weight and the r2 is calculated to be 0.86. Discussion The black mark at the tip of neonatal VYGON endotracheal tube is located at a fixed distance, regardless of the diameter. For the smallest neonates, the black mark will lie half-way and for the largest babies, more than the full length through the vocal cords. Conclusion Passing the black mark through the cords leads to bronchial intubation in extreme preterm babies, and high ETT for term infants. One cannot use the black mark to guide how far the ETT should be inserted beyond the vocal cords to be adequately positioned.

A discrimination method for the detection of pneumonia using chest radiograph

This paper presents a statistical method for the detection of lobar pneumonia when using digitized chest X-ray films. Each region of interest was represented by a vector of wavelet texture measures which is then multiplied by the orthogonal matrix Q 2. The first two elements of the transformed vectors were shown to have a bivariate normal distribution. Misclassification probabilities were estimated using probability ellipsoids and discriminant functions. The result of this study recommends the detection of pneumonia by constructing probability ellipsoids or discriminant function using maximum energy and maximum column sum energy texture measures where misclassification probabilities were less than 0.15.

Qualitätskontrolle von Röntgenthoraxaufnahmen bei Kindern in diagnostischen Zentren mit und ohne kinderradiologische Kompetenz

Radiation protection in pediatric radiology is very important because of the particular sensitivity of radiosensitive organs in younger patients. Optimized image quality supports radiation protection and should be targeted. In our study we examined the quality of pediatric chest X-rays at diagnostic centers (university hospitals and other large clinics). We then evaluated differences in image quality in departments without pediatric competence (R) and departments with pediatric competence (PR). Our study was based on 313 conventional chest X-rays from 207 patients (192 p. a./a. p. and 121 lateral, 43 from R, 258 from PR and 12 neither from R nor KR) and 38 digital chest X-rays from 26 patients (25 p. a./a. p. and 13 lateral, 1 from R and 37 from PR). All patients (age 0 - 18 years) are from Nephroblastoma-Study SIOP-93/01-GPOH. We examined all initial chest X-rays, which were sent to us for evaluation upon request between 4/3/2002 and 6/14/2002. The examined parameters were: exposure, centering of the X-rays/patient positioning, collimation and sharpness. The X-rays were evaluated on a scale from 1 (best result) to 5 (worst result), resulting in an overall score of A = optimum, B = minor problems, C = major problems, or D = unusable. The optical density, the center of the image and the relative field size were also measured. Statistical tests (Mann-Whitney-U and log regression) were carried out on the conventional images. The study was performed retrospectively. The exposure, sharpness and optical density of the digital X-rays were not analyzed. In the case of all conventional X-rays, the quality of the centering of the X-rays/patient positioning and collimation was moderate (average scale value: 2.4 and 2.8), and the quality of the exposure and sharpness was good and very good (average scale value: 1.9 and 1.5). The quality of the chest X-rays in departments with additional pediatric radiological expertise was better mainly in the case of younger patients (younger than 5 years) than departments without additional pediatric radiological expertise (average scale value in age group 0 - 1 month: PR = 1.7; average scale value in age group 2 months - 2 years: R = 2.4 and PR = 1.8; average scale value in age group 3 - 5 years: R = 2.5 and PR = 1.8). Despite the good overall image quality, the quality of the centering of the X-rays/patient positioning and collimation was insufficient in both examiner groups (R and PR). For this reason, some radiation protection requirements could not be fulfilled. X-rays from PR were higher quality than X-rays from R in this special study group. Day-to-day quality checks are necessary for pediatric chest X-rays in order to achieve a high quality standard.

Routine Chest Radiography Following Imaging‐Guided Placement of Tunneled Central Lines: A Waste of Time, Money, and Radiation

This study sought to evaluate routine chest radiography following placement of tunneled central lines using combined ultrasound and fluoroscopic guidance. A prospective study of 150 consecutive patients who underwent placement of tunneled central lines in the vascular radiology suite. Ultrasound-guided vein puncture was performed with an 18-gauge needle in each case, and the access site was noted. Line position was confirmed by fluoroscopy. Following the procedure, 50 patients had both an on-table digital chest radiograph and a conventional chest radiograph. Subsequent patients had a digital radiograph and a fluoroscopic image grab. Final line tip position was scored, and complications were recorded. Line placement was optimal (95%) or acceptable (5%) in all patients. Line tip position could be satisfactorily evaluated on supine fluoroscopy. Mean fluoroscopic x-ray dose was 0.5 cGy/cm2. Digital chest x-ray dose was 9.0 cGy/cm2, and formal chest radiography dose was 12.0 cGy/cm2. The only complications were 2 carotid artery punctures without clinical sequelae. When lines are placed under imaging guidance with ultrasound to direct the venous puncture, complications are rare and are not likely to be clinically important. Conventional and digital chest radiographs do not contribute clinically relevant information but do add to the radiation dose, time, and expense of the procedure.

Image quality of digital chest X-rays: wet versus dry laser printers

The aim of this study was to compare the image quality of digital chest x-rays (Thoravision) obtained with 2 "wet" laser imagers of different matrix sizes and a "dry" system. Fifty chest x-rays in 2 planes were printed out in normal (100%) and reduced (61%) format using 3 different systems: 2 "wet" laser imagers (Agfa Matrix LR 3300, 4256 x 5174 pixels, 315 dpi; Agfa Scopix LR 5200, 8512 x 10348 pixels, 630 dpi), and one "dry" system (Agfa Drystar 3000,4352 x 5295 pixels, 330 dpi). All tests yielded normal findings. Anonymous images were evaluated by 4 independent reviewers on record forms rating the detectability of predefined anatomic structures. When the image quality of diagnosis-relevant, anatomic structures was evaluated on digital chest x-rays reproduced in normal and reduced format, the wet laser imagers did not show significant advantages over the dry system, Agfa Drystar 3000. The Agfa Drystar 3000 system is a feasible alternative for reproducing digital images, particularly for decentralized archives.

Towards image quality, beam energy and effective dose optimisation in digital thoracic radiography.

This paper outlines how objective measurements of both image quality, in terms of signal-to-noise ratio, and effective dose may be used as tools to find the optimum kVp range for a digital chest radiography system. Measurements were made with Thoravision, an amorphous selenium-based digital chest X-ray system. The entrance surface dose and the effective dose to an anthropomorphic chest phantom were determined demonstrating how effective dose is related to beam quality. The image quality was measured using detective quantum efficiency, threshold contrast and a radiologist preference trial involving 100 patients. The results show that, despite the fact that the entrance surface dose decreases as the kVp increases, the effective dose, a better measure of the risk, reaches a minimum value between 90 and 110 kVp; however, the image quality decreases as the kVp increases. In this study the optimum kVp for chest radiography, using a selenium-based radiography system, is in the range 90-110 kVp. This is contrary to the 120- to 150-kVp range that is commonly used. Also, this study shows how objective measurements can be used to optimise radiographic technique without prolonged patient trials.

Can chest X-rays and ventilation/perfusion scans be interpreted reliably from personal computer screens?

A computer-based system is routinely used for home reporting of nuclear medicine scans performed out of hours in our unit. To report ventilation/perfusion scans (V/Q) adequately, chest radiographs are also digitized and transferred to the home personal computer. One hundred consecutive V/Q scans and their corresponding chest X-rays were reported on a personal computer and on a lightbox by two radiologists and two nuclear physicians. This study shows that ventilation/perfusion scans can be reliably reported from computer screen images. The loss of data when chest X-rays are digitized to a 512 x 512 matrix, however, results in considerable misinterpretation and the digitized chest X-ray may, at best, be unhelpful and, at worst, result in an incorrect V/Q scan report.

Are Digital Chest X-rays Good Enough?

I am writing about the growing use of digital radiography (teleradiology) for chest x-rays. I solicit responses from other more knowledgeable chest physicians regarding their experience and recommendations for this new technology.

Downstaging of Stage C Prostatic Carcinoma by Inductive Chemo-Hormonal Therapy?

One hundred and three patients with clinical stage C prostatic carcinoma (palpable extra-organ extension) underwent inductive chemo-hormonal treatment followed by radical retropubic prostatectomy with pelvic lymphadenectomy. First a careful noninvasive tumor staging was performed, which included a thorough digital rectal palpation, PSA, PAP, chest X-ray, bone scan, IVP, transabdominal and transrectal ultrasonography, CT and MRI. Then inductive chemo-hormonal therapy commenced. It consisted of total androgen deprivation plus the administration of cDDP or 5-FU + calcium folinate + mitomycin. After completion of chemotherapy (i.e. 4 months later), noninvasive staging was repeated. Then radical prostatectomy was carried out, followed by histologic work-up of the specimen. Postinductive, noninvasive examinations showed clinical downstaging in 49 of the original 103 patients (47.5%). Histopathology showed confinement of the tumor to the prostate in 40 specimens (38.8%). These results prove that chemo-hormonal induction is highly effective and suggest strongly but do not prove definitely histological downstaging in a significant percentage of the patients.

A method to measure the MTF of digital x-ray systems.

A method has been devised to accurately measure the modulation transfer function (MTF) of digital x-ray systems up to and, for undersampled systems, beyond the pixel Nyquist frequency (fN). A phantom consisting of an array of parallel tungsten or similar wires is imaged, and discrete Fourier transforms of rows of pixel values are computed. Under suitable conditions of phantom orientation, wire diameter, wire spacing, and image magnification, the envelope of the modulus of the mean Fourier transform represents the system MTF. Experimental results extending beyond fN are presented for an undersampled prototype digital chest x-ray system and shown to be in reasonable agreement with predicted values. Employment of the method with other digital imaging modalities [i.e., computerized tomography (CT) scanners and nuclear magnetic resonance (NMR) units] is also discussed as well as error considerations and practical problems in implementing the method.

An image processing system for digital chest X-ray images

This paper investigates the requirements for image processing of digital chest X-ray images. These images are conventionally recorded on film and are characterised by large size, wide dynamic range and high resolution. X-ray detection systems are now becoming available for capturing these images directly in photoelectronic-digital form. In this report, the hardware and software facilities required for handling these images are described. These facilities include high resolution digital image displays, programmable video look up tables, image stores for image capture and processing and a full range of software tools for image manipulation. Examples are given of the application of digital image processing techniques to this class of image.